(1) Field of the Invention
The present invention relates to a liquid crystal display device, and in particular, to a technology which is effective when applied to an active matrix type TFT liquid crystal display device.
(2) Related Art Statement
Conventional liquid crystal display devices having a liquid crystal display panel where a liquid crystal material is sealed between a pair of substrates include active matrix type TFT liquid crystal display devices. The above described active matrix type TFT liquid crystal display devices (hereinafter simply referred to as liquid crystal display devices) are used for monitors, such as televisions and PC's (personal computers), and displays for portable electronics, such as portable phones.
In the liquid crystal display panels used in the above described liquid crystal display devices, a number of scanning signal lines, a number of video signal lines, a number of TFT elements (active elements) and a number of pixel electrodes are provided on one substrate (hereinafter referred to as TFT substrate) from among the above described pair of substrates in such a manner that the set of pixels having the above described TFT elements and pixel electrodes connected to the above described TFT elements form a display region.
In addition, a light blocking film (which may be referred to as black matrix) and color filters, for example, are provided on the other substrate (hereinafter referred to as a facing substrate) from among the above described pair of substrates in the above described liquid crystal display panels. The above described light blocking film is formed of, for example, a conductor or an insulator in mesh form which divides the display region into microscopic regions for each pixel, and in general, extends in such locations as to overlap (face) scanning signal lines, TFT elements and video signal lines on the above described TFT substrate. In addition, the color filters are provided to liquid crystal display panels for color display, and in the case of an RGB type color liquid crystal display panel, for example, red (R), green (G) and blue (B) color filters are provided.
In addition, in the case where the above described liquid crystal display panel is of a drive system, which is referred to as a longitudinal electrical field drive system (for example, VA system or TN system), counter electrodes (which may also be referred to as common electrodes) which make pairs with the above described pixel electrodes are provided on the above described facing substrate. In addition, in the case where the above described liquid crystal display panel is of a drive system (for example, IPS system), which is referred to as a lateral electrical field drive system, the above described counter electrodes are provided on the above described TFT substrate.
In addition, in the case of conventional general liquid crystal display devices, one TFT element and one pixel element are effective in one pixel. In the liquid crystal display devices that have been proposed in recent years, however, one pixel is divided into two sub-pixels so that two effective TFT elements and two effective pixel electrodes are provided in this one pixel (see, for example, Patent Document 1).    (Patent Document 1) Japanese Unexamined Patent Publication 2006-309239 (Corresponding U.S. Application US2007/0008263 A1)